Electric overload circuit breaker with bi-metallic latch operable on low amperage



Jan. 28, 1958 R. c. INGWERSEN v2,821,601

ELECTRIC OVERLOAD CIRCUIT BREAKER WITH BI-METALLIC LATCH OPERABLE ON LOW .MMFERGE Filed April 28, 1954 INVENTOR ATTORNEY UnitedStates lPatent O w ELECTRIC OVERLOAD CIRCUIT BREAKER vWITH BI-METALLIC LATCH OPERABLE` N LOW AMPERAGE Application Aprilzs', 1954, seriarNo. 426,111

2 claims. (c1. zoo- 116) This invention relates to electric overload circuit breakers of the kind which employ a bi-metallic latch, in electrical conductive connection with a pair of movable contacts and adapted to be held closed against companion fixed contacts by the actuation of a re-set plunger, with respect to which the latch and movable contacts are slidable as a unit by springaction to suddenly and automatically interrupt the circuit upon the current attaining a predetermined overload value. In particular the invention is concerned with a modification or improvement in the electric overload circuit breakers disclosed in U. S. Patent No. 2,485,736 in my name and dated October 25, 1949.

In the circuit breaker disclosed in said prior patent the bi-metallic latch is formed by a pair of spaced apart parallel U-shape parts interconnected by integral transverse bridge portions, to which a pair of contact arms carrying the movable contacts are connected. The .U- shape parts are mounted and arranged to have edgewise latching engagement with abutment surfaces located upon opposite sides of a re-set actuator plunger. With thls prior construction the current flow takes place in parallel through the opposed U-shape latch parts with the result that this imposes a limitation upon the minimum current vrating at which the latch may be made effective if it is taken into account that there is a limit as to the permitted thinness of the latch parts if the same are to have suicient mechanical stability as to enable them to be held engaged edgewise with their abutment structure.

It is an object of the present invention, therefore, to provide an improved or modified construction and arrangement of the bi-metallic latch and movable contact assembly according to the said prior patent which enables the assembly to be employed to operate effectively at such a low amperage as, for example, 5 amperes.

It is also an object of the invention to provide a bimetallic latch and movable contact assembly for use on overload protective electric circuit breakers which enables the overload protection to be effective at a very low amperage rating, such as is required, for instance, on certain electronic and other electrically sensitive devices.

Further and other objects and advantages of the invention residing in the construction, arrangement and combination of parts will appear clear from consideration of the following detail description with reference to the accompanying drawings and from the appended claims.

In the drawings: v-

Figure l is a perspective plan view of a bi-metallic latch and movable contact assembly in accordance with the invention, and

Figure 2 is a vertically exploded view of the assembly as seen in Figure 1.

Referring to the drawings 10, indicate a pair of electric conductor arms carrying contacts 12, 12' and 14, 14 indicate a pair of separate Ushape bi-metallic latch parts.

At their inner ends, remote from the contacts 12, 12', (which form the movable contacts of a circuit breaker in 2,821,601 Patented Jan. 28, 1958 ICC 2 which said assembly is to be employed) each said arm has a hole 16 for receiving a rivet, the heads of which are seen at 18 and which serve to affix the diametrically opposite inturned flange portions 20, 22 of the U-shaped parts to the conductor arms 10, 10', respectively, bythe engagement of the rivets in the flange holes 24.

A rectangular frame of electrical insulating material is ill-ustrated in the exploded view of Figure 2 as having holes 28 through which the aforesaid rivets pass and having further holes 30 through which further rivets 32 pass to secure one end of a pair of conductor links 34 to the opposite ends of said frame, the rivets 32 passing through holes 30' in said links and the links having further holes 36 at their opposite end through which further rivets, the heads `of which are indicated at 38, secure the said links to the inturned projections 40 on a rectangular conductor frame 42. These links 34, by being connected at one end to the projections 40 of the conductor frame 42 and at their opposite ends to the insulator frame 26, give stability to the otherwise free ends of the U-shape latch parts, as represented by the diametrically opposite inturned llanges 44, which flanges have holes 44 matching with the aforesaid holes 30 and receiving the rivets having the heads 38.

The conductor arms are optionally provided with depending projections 16 for location in slots 26 in the insulator frame 26 so as to hold the conductor arms against lateral displacement, which arms are held against turning by being riveted to the conductor frame 42, as indicated at 46. The projections serve for the attachment of one end of the coil springs 41 which are tensioned when the latch and contact assembly is set against its abutment structure, as disclosed in said prior Patent No. 2,485,736. The upstanding flanges 48 on the conductor frame 42 are also optional and if present serve as guides with respect to the actuator plunger (not shown) on which the movable contact and latch assembly is mounted.

With the construction and arrangement of said assembly as above described and illustrated in the drawings, and with the assembly incorporated in an electric circuit breaker constructed and arranged to operate in accordance with the disclosure in the aforesaid prior Patent No. 2,485,736, current flowing from contact 12 and along the conductor arm 10, for example, ilows via the latch part 14 from the llange 20 to the flange 44 and, from this flange, is conducted by the conductor frame 42 to the llange 44 of the opposite latch part 14. This conductor frame provides an electrical path for the current flow from said latch llange 44 to the llange 44 of the opposite latch part 14 and hence to the other conductor arm 10' and the `other Contact 12. lt will be appreciated, therefore, that the current llow through the latch parts takes place in series.

I claim:

l. ln an electric circuit breaker having overload protection, a combined bi-metallic and movable contact assembly comprising a laterally spaced separate pair of U-shape bimetallic parts each having inturned llanges at the ends of the legs thereof and a contact carrying arm connected to one said flange of each U-shape part, a common conductor frame connected with the other ange of each U-shape part so that current llow takes place serially through said parts, said conductor frame connecting the diagonally opposite llanges of said U-shape bimetallic parts, an insulator frame, and link means connecting said other anges with said insulator part to afford lateral stability to said other langes.

2. In an electric circuit breaker having overload current protection, a movable contact and bi-metallic latch assembly adapted to be supported for rectilinear movement with respect to lixed contacts for opening and closing a circuit, said assembly including a pair of spaced apart U-shap'ed bi-metallic latches adapted to engage lHired ahitrnerit structure Within a circuit breaker, each of said latches having inturned flanges at the ends of the legs thereof, a `pair of spaced apart contacts each connected with one ange of 'each latch and adapted to engage the Xed contacts, and a rigid conductor frame connected with the other flange of each latch so as to support said latches in spaced apart relationship and electrically interconnecting said latches so that current will oW from one contact to the other through both U-shaped latches in the vsarne direction and in series whereby said latches can be actuated by relatively low amperage.

References Cited in the file of this patent UNITED STATES PATENTS Angell Dec. 12, 1933 Jennings Feb. 9, 1937 Frank et al Ian. 28, 1941 Ingwersen Oct.`25, 1949 Ingwersen Ian. v13, 1953 Casey Dec. l, 1953 Elliott Dec. 29, 1953 FOREIGN PATENTS Switzerland Ian. 16, 1936 Switzerland July 1, 1947 

